The games are really a single game with a few options tuned for each of the three settings, and different set of careers for each, sold as three different books. The Warhammer 40K games had much bigger differences—here they are clearly written with cross-playing in mind from the beginning.
Despite those reservations, I had no compunction about joining a game, when my long-time GM grabbed a cheap starter kit and organized a game. We got characters from the Age Of Rebellion starter kit and entered the fray (though he wrote his own adventure). The first game was a blast, though getting used to the system took a bit and we are still getting used to symbols (though triumphs and despairs are quite recognizable already). After the first session we got an option to tweak the characters we selected but continued further with them. A second group was also formed by the same GM with partial player overlap, and as for now it proceeds happily until we get bored and burned out by Star Wars.
The game mechanics are not very complex, despite the initial appearance otherwise. There are seven types of dice: three positive dice, three negative dice, and force dice. Positive dice contain positive symbols: success, advantage, and triumph. Negative dice are covered with negative symbols: failure, disadvantage, and despair. Successes an failures cancel each other, as do advantages and disadvantages. The former decide if the roll was successful (and to what degree), the later grant additional side effects, positive or negative, such as activating special abilities (Auto-fire! Zap-Zap-Zap!), scoring critical hits, gaining extra information, recovering from fatigue, or getting better position that will grant you (or an ally) bonus dice to the next roll, or in case of disadvantages causing extra strain, granting bonus dice to your enemies, or meaning you're out of ammo. Triumph counts as successes and grants bigger positive effect than regular advantage. Despair counts as failure and grants big negative effect. This allows the roll to have following results: success, failure, success with positive side effects (e.g. you shot opponent and destroyed the alarm console without triggering it), success with negative side effects (you shot an opponent and the console but it triggered the alarm), failure, failure with positive side effects (you missed the shot but you destroyed the console), failure with negative side effect (you missed and alarmed everyone). Plus the possibility of big special effects. It makes sense in play, though counting the symbols is not as fast as it could be with some other design.
The positive and negative dice are mirrored: there is one type of positive eight-sided die (green ability die) representing basic abilities and one negative eight-sided die (purple difficulty die) that represent difficulty of the action (instead of more typical fixed number of successes needed to succeed). Each of their sides contains a different combination of successes/advantages for ability dice, and failures/disadvantages for difficulty dice. The better dice are twelve-sided: yellow competence die, that represents upgrade of ability with actual skill, and red challenge die, which shows that opposition upgrades the difficulty. Each contains a combination of either successes and advantages or failures and disadvantages, but they also introduce triumph and despair symbols. The remaining two dice types are six-sided: blue boost die and black setback die, that are added to the pools to represent various conditions, bonuses, and penalties with lesser degree of impact than skill and ability. They contain successes, advantages, failures, and disadvantages, but no triumph or despair symbols.
The seventh type of die has no twin, for it is a force die with white (Light Side) and black (Dark Side, duh) dots. It is used to generate destiny pool at the start of the game, and force points when using force powers.
Rolling the dice involves creating a dice pool based on the acting character's ability scores and skills, adding difficulty dice, then adding boost and setback dice based upon internal (talents) and external circumstances (equipment, results of previous rolls, aid of others, aiming). There are some effects that allow upgrading ability and difficulty dice into competence/challenge dice, or downgrading the later into the former, like turning the Destiny tokens from Light to Dark side (players) or vice versa (GM). Creating the dice pool can be fun or it can get tedious, with all the cajoling, begging, or negotiation with GM what should get you net you a bonus or why you shouldn't get a penalty. Oh, and don't forget to apply your talent or equipment bonuses... This is not really that different from applying bonuses and penalties of more conservative rolling conventions, but it's really appealing visually—you actually see your bonuses and penalties as dice of different colors, which makes the experience refreshing.
The fights can be brutal, though the game cinematically assumes player characters and major NPCs don't die until a critical hit says the character died, which requires suffering multiple critical hits or a particularly lethal weapon (disruptor). Critical hits are suffered when the attacker decides to spend his advantages or triumph to deal one (the more dangerous weapon the less advantages are needed to do this, a standard blaster requires four advantages, rifle three, disruptor and vibro weapons two), or when character suffers more wounds than his wound threshold. When a critical hit is dealt, a 1d100 roll is made, with additional +10 for each unhealed critical hit, and the table is consulted. The first half of the table is mostly temporary results, the second half of the table is bad. The third half (i.e. results above 100) are terrible, with death being certain with totals exceeding 150 (and probably even earlier, haven't looked on that part of the table much). Cooperation is important, both for attack and defense. Healing wounds between fights is vital, making Medicine skill and stimpacks key resources—the later heal a few wounds as a maneuver (you can stick oneself with one and keep firing in the same turn), though their effects get progressively weaker with each use on the same day. Full bacta tank is you best friend forever if you are front-line fighter (or Duros spy), as it heals wounds and allows regeneration of critical hit results each day, instead of once a week. Besides slowly healing wounds, and very slowly healing critical hits, each character can also suffer strain from non-lethal attack and misadventures, or deliberately used to perform extra maneuvers. It is recovered more quickly, with a night of rest removing all of it.
The characters have six quite conventional ability scores: Brawn that determines combined strength and physical resistance, Agility, Intellect (which covers knowledge and technical skills), Cunning (which is basis of deception, perception, thievery, streetwise, and survival) Willpower, and Presence. They are scaled from 1 to 6 and determine number of dice in your pools, and set some secondary characteristics such as wound threshold, strain threshold, soak, and maximum encumbrance. Ability scores are followed by 30-something skills that turn your green ability dice into more desirable yellow competence dice (more successes and advantages, chance of rolling triumphs), including the Star Wars essential skills like Gunnery (i.e. vehicular weapons), Piloting (Space), Ranged (Light), Ranged (Heavy), and for those who are playing Force And Destiny, Lightsaber.
Each character belongs to one of the species (there are multiple races per core rulebook, and more in expansions but the game misses the guidelines for creating own playable species), a career, and one or more specializations. Each game has six careers with three specialization talent trees in the core rulebook, and three more specialization in the expansion book for that career. There is some overlap between specialization in Age Of Rebellion and Edge Of The Empire, for example AOR spy shares slicer specialization with EOTE technician and scout specialization with EOTE explorer.
Career and the first specialization determine starting skills, specializations learned determine access to talent trees. You need to learn a specialization to learn any of its talents (thought there is some overlap between talent trees) but you can learn any skills and any new specializations regardless of your career, doing it outside of your career merely costs more experience points. Talents grant you passive bonuses (Dedication, a talent that increases single ability score is usually at the bottom at each tree—they start at the top and the talents have to be purchased following the available connections), modify effects of some maneuvers and actions, or can grant you access to completely new actions (such as using stimpack to increase ability scores instead of healing).
If you have a force career, or one of two universal force specializations you gain Force Rating 1, which you can increase with, you guessed it, right talents, and now you can select force powers, which work similarly to talent trees dedicated to specific power, such as Move, Sense, Heal/Harm, or Foresee. Force-users are feeling quite balanced, comparing with other characters due to excessive experience cost involved in developing them fully. At least until you run into an Inquisitor NPC who can kick the party's collective backsides until they have many-many sessions behind them.
Age Of Rebellion careers are aces (drivers, gunners, and pilots), commanders (leaders of men on ground and in space), diplomats (ambassadors, agitators, and quartermasters), engineers (mechanics, saboteurs, and scientists), soldiers (commandos, medics, and sharpshooters), and spies (infiltrators, scouts, and slicers). It also offers two universal specialization: recruit to allow making more combat-oriented characters out of non-combatants, and force-sensitive emergent, which is used to represent people who discover they are sensitive to force. Yes, anyone can develop force abilities by selecting the specialization. Players are intended to be heroes. Even if Stormtroopers can easily handle them early on.
Edge Of Empire careers are bounty hunters (assassins, gadgeteers, and survivalists), colonists (doctors, politicos, and scholars), explorers (fringers, scouts, and traders), hired guns (bodyguards, marauders, and mercenary soldiers), smugglers (pilots, scoundrels, and thieves), and technicians (mechanics, outlaw techs, and slicers). It offers single universal specialization: force-sensitive exile, someone accustomed to hiding own fledgling powers since forever.
Force And Destiny careers have no overlapping specializations with the previous games, offer less starting skills, but also get Force rating 1 from the start: consulars (healers, Niman disciples, and sages), guardians (peacekeepers, protectors, and Soresu defenders), mystics (advisors, Makashi duelists, and seers), seekers (Ataru strikers, hunters, and pathfinders), sentinels (artisans, shadows, and Shien experts), and warriors (aggressors, Shii-Cho Knights, and starfighter aces). Each career contain single specialization dedicated to one of the lightsaber forms. Five of those offer talents that allow using lightsaber skill with ability score different than the default Brawn—you can make flamboyant Makashi duelist, agile Ataru striker, or thoughtful Soresu Defender... No universal specializations here, though.
Each of the games has expansion books dedicated to various careers (I think that at least half or even more careers have their own books by now), some adventures, and some non-class expansions, such as book dedicated to planets that support the Rebellion for AOR, book about Hutts and their space for EOTE, and one describing a few places of power for F&D.
Character creation of all of those games is wonderful because of a single thing: there is an excellent fan-made character generator: OggDude's character generator. A lot of professional programs show less quality and attention to detail.
Each of the games offers a unique mechanic to help direct characters: AOR has Duty, a measure of the party's achievements that can be accumulated by supporting the rebellion in various ways to increase the party's standing within the Rebellion ranks. EOTE has Obligation, a sum of the individual character's debts, connections, and past deeds that peek from time to time to bite their exposed undertails. F&D has Morality which shows the force-sensitive character's equilibrium between Light and Dark sides of the force (joining the Dark Side has some bonuses, some penalties, and a significant power boost, but requires serious balancing to avoid losing oneself fully to the Dark Side and turning into an NPC).
To top it, the game rules are well streamlined for vehicular combat, with well developed array of planetary and space vessels. You can improve your gear and vehicles with attachments and modifications... We need to get cash for parts to improve some of our own, yet. Have I mentioned that OggDude's character generator covers crafting and modifying your equipment and your vehicle too?!
The negatives: the need for a new set of dice (or better two), getting used to them and crappy default character sheets that don't show clearly the dice you need to use for your skills (though if you can allow oneself to print character sheet each time you change stats, or simply use electronic device, the OggDude's generator comes to the rescue again).
Anyway the game is much fun, even for people that might be ignorant of the Star Wars (half of one party is composed of players who watched some of the Star Wars movies after they started playing). Obviously, after some time of playing the it will lose the status of the novelty, and we will suffer the burnout of the system and the setting, and we'll take a break from it, but no game lasts forever.